voltage regulator adjustment need for agm battery???? (1 Viewer)

Joined
Apr 4, 2012
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17
Location
moncton., nb. canada
hi guys., 1980 fj40., 40 amps alternator......just put in agm red top battery(2 months ago) pamphlet with battery says needs for charging 13.8 to 14.4. my voltage regulator worked well with a regular flooded battery.....but a bought an agm for safety (i thought) . when daytime driving my battery stays well charged up but when i drive at night with lights on and fan ., i check my battery an i find it at 12.34 so well below the 12.87 full charged.....my question is can i adjust my VR to raise the amount of charging w/o damaging my wiring an charging my agm as needed? your input would be very welcome as usual thanks...ps my 2018 f150 with agm battery goes up to 14.5 at least when my headlights and accesoiries are on.....i know we can't compared both but....just saying...
 
Joined
Mar 3, 2012
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982
Location
Adelaide, South Australia
Just the factory headlights.. or some others as well? The heater fan is a big current consumer.

You may be reaching the limit of your 40A alternator.. a DC clamp meter is invaluable in a situation like this. I would not be adjusting your regulator prior to assessing current draw.
 
Joined
Feb 4, 2014
Messages
7,168
Location
Las Vegas
Sorry, I can’t answer your AGM question... but, should you elect to look into your VR, Rudi (@bj40green ) describes it and explains how to adjust it here —> Voltage Regulator (ext.) / How it works

Remember you have to be turning at least 2000 rpms to cause the VR to tell the alternator to charge... I presume you are turning at least 2k rpms at night...

You might also consider LED headlights/lights, to significantly lower your electrical draw.
 
Joined
Mar 24, 2020
Messages
20
Location
Rhode Island
low voltage leads to higher amp draw. 12.34v is not low enough to damage circuits, but it is lower than I would want it. agm batteries require a higher charging voltage than wet cells. charging an agm at a lower voltage will shorten the life of the battery.
 
Joined
Apr 4, 2012
Messages
17
Location
moncton., nb. canada
i changed my VR and with all acc. on (1200 rpm) i get 12.87 volts on my multimeter....will see if that enough to keep my agm battery happy...thanks guys.....
H4 headlight on high beam., fan on max. , and wiper on..
 

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